A three-fold approach to neural plasticity within the framework of a program-project grant concentrating on: (A) An inquiry into the presumed role of "feature-detecting neurons" in the brains of mammals, including man, with emphasis on the possible functions of these neurons in the early postnatal development of perception and on the extent to which these neuronal mechanisms might be modified by varied kinds of exposure. (B) An exploration of the degree and limits of "structural plasticity" shown by the brain of young mammals, particularly in their responses to early cerebral lesions, together with a continuing effort at identifying functional "markers" for the progressive specialization of cerebral systems, from infancy into adolescence. In its extension to our own species, this work turns increasingly on the question of how the two cerebral hemispheres of the human brain, the right and the left, play complementary roles as the child grows up. (C) a concerted attack on problems of development and maintenance of plastic visuomotor coordinations. Here the major sub-topics for investigation concern the role of motility, including "active" vs. "passive" exposure, in the adaptation of humans and animals to stereotyped or distorted sensory inputs; the search for neural correlates of motor programs and, particularly, attempts at characterizing, in neural terms, the differences in levels or strategies, in primates, of complex coordinated movements, from those movements that are least "voluntary" (e.g., visually triggered) to those that are least dependent on ongoing stimulation (e.g., spontaneous searching). Recovery of function, after peripheral or central lesions of nervous connections, can be shown to proceed quite differently, we believe, depending on the level of motor organization that is involved.